Snap action electric switch



Dec. I2, 1950 w. SHARP SNAP ACTION ELECTRIC SWITCH Filed May 21, 1948 Invento: WILL/HM SHARP "WW5 ,9

Fatented Dec. 12, 1950 UNITED STATES PATENT OFFICE Application May 2-1, 1948,,SerialNl1. 28,397

In Great Britain March 20, I948 2 Claims; g

Thisinvention' relates to snap-action electric switches of the; type having a frame, a butt contact fixed in relation to the frame, a switch arm pivoted on the frame, a link pivotally'mounted on the switch arm outwardly of the switch arm pivot, and particularly relates to cam operated switch-es for control gear. According to this invention the terminals of the switch are arranged on one side of the latter, thereby avoiding: the need of having to carry a heavy conductor from one side of the switch to the other. By this invention also the switch is more conveniently fitted and is not liable to be distorted on its fixing base.

In the drawing, an embodiment of the invention is illustrated, of which Figure 1' is aside elevation of a control switch in off position, parts of the frame being broken away for convenience of illustration.

Figure 2 is a cross-sectional elevation of th switch in "on position, and

Figure 3 is a section taken on line IIIIII of Figure 1.

According. to a convenientembodiment of this invention, the switch comprises a frame member I fixedly mounted on an insulating base a. The frame conveniently comprises an aluminium bronze casting to form an electric conductor for carrying a large current. The switch arm 2 is pivotally mounted on a pivot pin 3 passing transversely through the frame I. is formed by two levers arranged on each side of the frame I and carrying the cam operated roller 4 at the rear of the arm. A lever or link 5 is pivotally mounted at B on the switch arm at the rear of said frame I and such lever or link 5 extends forwardly on each side of the frame I to project beyond the front of such frame. The lever pivotally carries a movable contact carrying memher I which comprises a rectangular shaped metal block having trunnion pins 8 which engage slots 9 in the lever 5. A pin it is fixed to this block and project rearwardly and slidably and pivotally engages a perforation Illa in the frame I and passing between the bifurcated arms of the lever 5 in front of the pin pivoting such lever 5 to the switch arm 2. A spiral spring I2 is located between the frame and block I or a nut, locking the pin ID to said metal block or member "I. The movable switch contact comprises an L-shaped copper block I3 fixed to the end of the contact carrying member I. The fixed switch contact I4 comprises a similar shaped copper block fixed to the insulating base a and forwardly of the switch frame I. The faces of the blocks l3 and M are curved to permit of a slight roll The switch arm 2 during switch movement. The spring I2- aforementioned normally holds the switch lever 2 and the link 5- in a raised position with the switchopen. In order to close the switch, switch arm 2 is depressed about pivot on the frame i.- As the switch arm pivots downwardly towards the insulating base (see Fig. 2), the link 5 is pulled bodily rearwardly until the pivot axis of the link and switch arm is beyond the dead centre of the spring actuated device, when the lever 5- and contact carrying member It will snap over to press-the contacts it, [A together. The pivot axis 6 of the link 5 and switch arm- 2 will now have moved fro-m above the axis of the spring E2 t a position below the axis and on releasing the pressure on the switch arm 2', the switch will be moved into the off position by the action of the spring which re-acts by the pressure ofthe movable contact 53 on the fixed contact it to effect the opening movement and, whilst the contacts are thus spring pressed together, the upward movement of theswitch arm 2 bodily moves the link 5 forward and consequentlyslides the movable contact it onthe fixed contact (to the position shown by dotted lines Figure 2) thereby producing a shearing action which wouid' break down any possible welding of the contacts to gether. The supply main is connected to the terminal I5 of the fixed contact it and to the terminal It which comprises a bolt holding the frame I on the insulating base a. The current thus passes through the frame I and through the flexible lead H to the moving contact Thus the terminals I5 and it are positioned on the same side of the switch. As the frame i is formed of high conducting material, the need is avoided of having to connect the lead from the electric supply main to the inner end of the flexible conductor IT. The base of the frame i is slotted for easy assembly on the terminal bolt it.

It can thus be seen that there has been provided according to the invention a snap action electric switch which is essentially characterized by a frame forming an electrical conductor, a butt contact fixed in relation to the frame, a pivot on said frame, a switch arm movable about said pivot on said frame, a pivot on said switch arm, a link pivotally mounted on said pivot of the switch arm, a movable contact member pivotally mounted on and connected to the link, said movable contact member including a slide rod, the outer end of said rod being slidably and pivotally mounted in relation to the frame, an abutment block on said rod, a spring on said rod 7 bearing against said abutment block and said a flexible conductor connecting said frame to said movable contact, said pivot on said frame being located in one position of said spring below and in another position of said spring above said pivot on said switch arm from which said link extends to and pivotally engages said movable member.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. An electric switch comprising a frame forming an electrical conductor, a butt contact fixed in relation to the frame, a pivot on said frame, a switch arm movable about said pivot on said frame, a pivot on said switch arm, a link pivotally mounted on said pivot of the switch arm, a movable contact member pivotally mounted on and connected to the link, said movable contact member including a slide rod, the outer end of said rod being slidably and pivotally mounted in relation to the frame, an abutment block on said rod, a spring on said rod bearing against said abutment block and said frame to urge the rod away from the frame and to pivot the link away from the switch arm, so that when the switch arm is moved in either direction past the dead center of the spring, the movable contact will snap into or out of contact with the fixed contact, an insulating base on which said fixed contact is mounted, and terminal means on said base and connected to said fixed contact and said frame, respectively, and a flexible conductor connecting said frame to said movable contact, said pivot on said frame being located in one position of said spring below and in another position of said spring above said pivot on said switch arm from which said link extends to and pivotally engages said movable member.

2. A snap action electric switch comprising a base of electric insulating material, a fixed butt contact member including terminal connection therefor on said base, an electric conducting frame including terminal connection therefor on said base, a pivot on said frame, a switch arm swingable with one end about said pivot on the frame and extending in a direction away from said fixed contact, a pivot carried by said switch arm, a link movable about said pivot on said switch arm, a movable butt contact pivotally connected to said link and including a slide rod rigid with said movable butt contact, said slide rod pivotally and slidably engaging said frame at a point intermediate the position of said pivot connecting said link to said switch arm and the position of the said pivot connecting said switch arm to said frame, a spring on the rod urging the link to pivot away from the switch arm, said pivot connecting said switch arm to said frame lying intermediate said engaging point of said rod with said frame and said fixed contact and at a point intermediate said fixed contact and the pivot connecting said link with said switch arm, so that the said spring exerts a force urging the switch arm to slidably move said movable contact member away from said fixed contact member when pressure on said switch arm for closing the switch is released.

1 WILLIAM SHARP.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date r 1,368,228 Behrens Feb. 8, 1921 2,307,946 Parke Jan. 12, 1943 FOREIGN PATENTS Number Country Date 263,291 Germany Aug. 6, 1913 

